osmo-mgw: rename struct mgcp_trunk_config and symbol tcfg

rename struct mgcp_trunk_config to struct mgcp_trunk and the related
symbol name "tcfg" to "trunk" in order to better match the reality.

Change-Id: I02889dbf8149e139b1bd0326e13ce4c1aec867d1
Related: OS#2659
diff --git a/src/libosmo-mgcp/mgcp_sdp.c b/src/libosmo-mgcp/mgcp_sdp.c
index 01e7968..428bde6 100644
--- a/src/libosmo-mgcp/mgcp_sdp.c
+++ b/src/libosmo-mgcp/mgcp_sdp.c
@@ -557,7 +557,7 @@
 		if (rc < 0)
 			goto buffer_too_small;
 
-		if (endp->tcfg->audio_send_name) {
+		if (endp->trunk->audio_send_name) {
 			rc = add_rtpmap(sdp, payload_type, audio_name);
 			if (rc < 0)
 				goto buffer_too_small;
@@ -573,7 +573,7 @@
 		if (rc < 0)
 			goto buffer_too_small;
 	}
-	if (conn->end.packet_duration_ms > 0 && endp->tcfg->audio_send_ptime) {
+	if (conn->end.packet_duration_ms > 0 && endp->trunk->audio_send_ptime) {
 		rc = msgb_printf(sdp, "a=ptime:%u\r\n",
 				 conn->end.packet_duration_ms);
 		if (rc < 0)